It depends on how many people the killers would kill after their iteration with the doctor or the metakiller.
To the number of total future victims you add the number of killers for the metakiller. Then to the number of total future victims you rest the number of killers for the doctor. You compare both numbers, the smallest number win.
I do believe gorilla piss exists.
I do not believe drinking gorilla piss would grant you gorilla strength (citation needed).